Zodiac Letter Cipher Explained
The Zodiac Killer sent chilling letters to newspapers in the late 1960s and early 1970s. These letters often included ciphers, which are secret codes made of symbols and letters. The killer used them to taunt police and the public. He promised that some ciphers held his identity or clues to his crimes. Four main ciphers stand out in his letters.https://en.wikipedia.org/wiki/Zodiac_Killer
The first big one is the Z408 cipher. In August 1969, the Zodiac mailed three letters to different Bay Area newspapers. Each had part of a 408-symbol cipher. He demanded they print it on the front page or he would kill more people. A couple from Salinas, Donald and Bettye Harden, cracked it in about a week. The message talks about killing for slaves in the afterlife. It says, “I like killing people because it is so much fun.” But the last 18 symbols did not match perfectly. People still debate what they mean.https://en.wikipedia.org/wiki/Zodiac_Killerhttps://zodiackillerciphers.com/wiki/index.php?title=Encyclopedia_of_observations
Next came the Z340 cipher. On November 8, 1969, the killer sent a 340-symbol cipher to the San Francisco Chronicle. It stayed unsolved for 51 years. In 2020, a team of codebreakers used computers to figure it out. The message reads like a brag: “I hope you are having lots of fun in trying to catch me… I am not afraid of the gas chamber because it will send me to paradice all the sooner.” This was a huge breakthrough after decades of tries.https://en.wikipedia.org/wiki/Zodiac_Killer
The Z13 cipher is short and tricky. In April 1970, a letter to the Chronicle started with “My name is” followed by 13 symbols. Many call it the holy grail of Zodiac puzzles because it might spell the killer’s name. It has stumped experts for over 50 years. Recently, an amateur named Baber used AI to test millions of name ideas against suspect records. He claims a solution linked to the Black Dahlia case, backed by a former NSA codebreaker. But it is not proven yet.https://en.wikipedia.org/wiki/Zodiac_Killerhttps://www.latimes.com/california/story/2025-12-23/black-dahlia-zodiac-killings-connected-one-killer-theory
The Z32 cipher came in June 1970 with a Phillips 66 map of California. The killer marked Mount Diablo and said the cipher plus radians and inches would show a bomb site. It reads across three lines of symbols. Gareth Penn thought “radians” was key and tied it to crime locations. No bomb was found, and no one agrees on a solution.https://en.wikipedia.org/wiki/Zodiac_Killerhttps://ciphermysteries.com/other-ciphers/zodiac-killer-ciphers/zodiac-killer-z32
These ciphers used homophones, where one letter like E gets many symbols to hide patterns. Crowdsourcing online helped solve the Z340. The unsolved ones keep hobbyists busy. They mix letters, numbers, and odd shapes like circled 8s.https://zodiackillerciphers.com/wiki/index.php?title=Encyclopedia_of_observations
Sources
https://en.wikipedia.org/wiki/Zodiac_Killer
https://zodiackillerciphers.com/wiki/index.php?title=Encyclopedia_of_observations
https://ciphermysteries.com/other-ciphers/zodiac-killer-ciphers/zodiac-killer-z32
https://www.latimes.com/california/story/2025-12-23/black-dahlia-zodiac-killings-connected-one-killer-theory
https://www.zodiacciphers.com/zodiac-news/the-prints-compared-by-hamlet
